Yi-young is always cheerful and bright. Making ends meet with several part-time jobs, she dreams of becoming a full-fledged member of an orchestra as a timpanist. She, however, has a mysterious experience that gives her a hard time. One year ago, she was in a car accident and lost her memory of the day. Suffering from insomnia and nightmares, she can only sleep with a weird song of a tone-deaf singer. That singer, Chang Yun, has the worst vocal but plays the piano beautifully. The very reason Yun accepted the strange job is Yi-young's lost memory. What is the secret of the day that Yi-young was too shocked to remember Yun desperately wanted to find out?